The manufacturing of semiconductor devices such as integrated circuit (IC) chips utilizes wafers of various types. For example, semiconductor wafers serve as a substrate in which the various three-dimension IC structures are formed using a series of process steps. Once the IC chips are formed, they then need to be packaged, i.e., encapsulated in a support wafer to form the finalized IC device.
To perform lithography exposures either when fabricating the IC or when packaging the ICs, the wafer must be held very flat. This requires holding the wafer down to a very flat surface using a vacuum. To this end, vacuum chucks have been developed to support wafers during lithography exposures.
With the advances in semiconductor IC fabrication and packaging, the wafers have increased in size and tend to have larger amounts of deformation, i.e., deviation from perfect planarity. Unfortunately, when a deformed wafer is placed on a standard vacuum chuck, there is too much leakage to generate the pressure differential necessary to pull the wafer down to the chuck surface so that the wafer can be processed in a substantially planar state.